Using Namespaces to create Multiple Tabs

Namespaces enable you to create and manage tabs in parallels. The best way
to demonstrate namespace usage is with an example.

Let's assume your application provides a first level navigation menu
with 3 elements: :home, :dashboard, :projects. The relationship between
your tabs and your controllers is 1:1 so you should end up with the
following source code.

The project controller contains 3 actions and you might want to create a
second-level navigation menu. This menu should reflect the navigation
status of the user in the project page.

Without namespaces, you wouldn't be able to accomplish this task
because you already set the current tab value to :projects. You need to
create a parallel navigation menu and uniquely identify it with a custom
namespace. Let's call it :navigation.